Downhole apparatus such as tools used in the exploration and production of hydrocarbon reserves often require remote activation or deactivation downhole. Sometimes the apparatus is toggled between different states or modes of operation using an indexing mechanism incorporated into a tool string. The indexing mechanism may be activated or toggled using a signal from surface, such as an electromagnetic signal, or a variation in fluid flow or pressure (e.g. caused by a drop-ball). Other activation mechanisms may follow a predetermined sequence according to other inputs, such as a time delay.
Typically the indexing mechanism will include a sleeve or a piston that can rotate and translate axially relative to a tubular, such as an inner or outer mandrel. The relative movement of the sleeve is often defined by a cam path, such as a slot and pin arrangement between the sleeve and the mandrel. Often the sleeve will transmit forces downhole, such as to open or close valves or reconfigure tools mechanically, such as by extending or retracting members with the movement of the sleeve.